Articles conveyed on an inclined gravity-type roller conveyor over a substantial distance and slope accelerate as they advance along the conveyor and may attain a substantial velocity at the end of their traverse. The high velocity of the articles being conveyed is objectionable in that it presents various problems, such as the difficulty of stopping the articles, the damaging of the articles by impact with one another, and the tipping of the articles especially if they are relatively tall.
In an attempt to overcome the above problem, numerous gravity-type conveyors utilizing intermittently actuated brakes have been devised. However, to the best of Applicant's knowledge, none of these systems have been highly successful in view of the disadvantages which result therefrom, the primary one of which is that the system is not fail-safe.
One known gravity-type roller conveyor employing an intermittently actuated brake utilizes a plurality of rubber support rollers, which rollers have internal brakes associated therewith for intermittently stopping the rollers. However, experience with this type of conveyor has indicated that successful control of the rollers can be achieved only when the operating conditions are precisely controlled. When substantial temperature variations occur, such as occurs between summer and winter weather conditions, it has been found that the brakes do not always stop the rollers and thus proper control of the rollers, namely intermittent braking thereof, does not always result.
Another known roller conveyor has been developed which utilizes an elongated brake member positioned below the rollers and moved upwardly by inflations of a flexible hose for engaging the rollers for periodically braking same. In this manner, the rotation of the rollers and the advance of the articles along the conveyor is thus controlled. While this system is at least partially effective for controlling the rate of movement of the articles, nevertheless this system does possess several structural and operational features which has made its use less than satisfactory. Particularly, in this known system, the brake is applied to the rollers only when the hose is inflated or pressurized. Accordingly, when a failure in the inflating system or hose occurs, the brakes cannot be applied so that movement of the articles along the conveyor is uncontrolled. This thus results in the numerous undesirable effects which have been discussed above.
A further disadvantage of this known system results from the fact that the braking force as applied to the rollers is determined solely by the pressure developed within the hose and by the relative clearances and distortions which occur throughout the system. The system clearances, distortions and hose pressure thus must be controlled rather precisely in order to result in the desired magnitude of braking of the rollers. This known system also is structurally complex since the hose and elongted brake member are positioned between an elongated stationary frame member and the plurality of rollers, which rollers in turn are rotatably supported on the stationary frame. Access to the braking member and the hose, as for purposes of maintenance, is thus difficult.
The gravity-type roller conveyor disclosed in my copending application Ser. No. 567 608 does provide for desired conrol over the rate of movement along the conveyor, while at the same time overcoming the above-mentioned undesired structural and operational features of the known systems. The conveyor of this copending application is highly desirable since it permits a controlled intermittent movement of articles along a gravity-type roller conveyor, which conveyor does not utilize an intermittently actuated brake, but rather utilizes an intermittently actuated roller system coacting with a stationary brake.
While the conveyor of my copending application has proven to operate in a highly successful and desirable manner, nevertheless experience has indicated that further improvements and simplifications can be made therein which permit the overall structure and operation of the conveyor to be substantially simplified, thereby minimizing both the cost of manufacturing and assembling the conveyor, and at the same time minimizing the required maintenance while substantially improving dependability.
Accordingly, the present invention relates to an improved gravity-type roller conveyor which not only incorporates the desirable features disclosed in my above-mentioned copending application, but also incorporates additional structural and operational features which still further improve the structural and operational characteristics of the conveyor. Particularly, the improved conveyor of this invention utilizes a periodic and intermittent actuator disposed along only one side of the conveyor so that the rollers of the conveyor thus undergo a limited vertical pivoting with respect to the other side of the conveyor. When the rollers are pivoted downwardly into their lowermost position, such as when the actuating device is in its lowermost position, the rollers are moved directly into engagement with a brake for stopping the rollers. The actuating device in this improved conveyor preferably utilizes an inflatable hose which is positioned along said one side of the conveyor and, when inflated, causes lifting of the rollers to permit conveying of articles therealong, whereby the conveyor thus retains a fail-safe operation so that deflation of the hose will automatically lower the rollers against the brake to stop the roller rotation and hence stop the articles.
Another object of the present invention is that it does not require the use of slave pallets or other specially designed pallets.
Other objects and purposes of this invention will be apparent to persons familiar with structures of this type upon reading the following specification and inspecting the accompanying drawings.